The common yellow yam Dioscorea dumetorum has been used by herbalists and practitioners of West African folk medicine for treatment of diabetes, as a topical anesthetic as well as an arrow poison and as a bait for monkeys (see generally, Corley et al. 1985, Tetrahedron Lett. 26(13):1615-1618). Additionally, D. dumetorum tubers are used as famine food, although it is well-known that the yams must be carefully prepared by soaking for several days in running or salt water and boiling overnight. In fact several cases of serious poisoning have resulted from ingestion of improperly prepared tubers (Undie et al., 1986, J. Ethnopharm. 15:133-144).
For use in herbal medicine for treatment of diabetes, a decoction is prepared by steeping the peeled tuber in native gin, distilled from fermented palm wine containing about 30-70% ethanol (termed "kai-kai") for about three days. The decoction is boiled until the color changes from yellow to brown and then is administered to patients in small cupfuls. (Undie et al., supra).
In a preliminary investigation, Undie et al., (supra), have shown that crude extracts of D. dumetorum possess hypoglycemic activity when administered to experimental animals. The authors stated, however, that several constituents were present in the extracts and nothing could be known with respect to what constituent was responsible for the observed hypoglycemic effects.
Corley et al. (supra) has shown that a methanol extract of D. dumetorum contains alkaloids including dihydrodoiscorine and dumetorine which may have convulsive, toxic activity.